Alongside this secure “avionics world”, there exists a non-secure “open world” which is able to provide information to the users of the “avionics world”. By way of examples, mention is made of the onboard documents management system termed the “Electronic Flight Bag” or the “Internet” links with the outside. This “open world” must be able to be controlled by the same “CCDs” as those used for the “avionics world”. In particular, it must be possible with the same “CCD” to easily move the pointer P from a screen 10 of the “avionics world” to a screen 20 or a window of the “open world” as indicated in FIG. 1. The screens of the “open world” and of the “avionics world” are not necessarily differentiated. A large viewing screen can at one and the same time comprise display windows belonging to the “avionics world” and display windows belonging to the “open world”. In this figure and in what follows, the coordinates of the pointer P in the “avionics world” are denoted (Xa, Ya), and the coordinates of the pointer in the “open world” are denoted (Xo, Yo). However, this “open world” does not benefit from the same level of computer security as the “avionics world”. If no precautions are taken, it is therefore liable to disrupt or disturb the operation of the “avionics world” through the common control of the “CCDs”.
To ensure this security, it is necessary that the management of the displacement of the pointer is handled by the “avionics world” in all cases, whether the pointer lies in a window of the “avionics world” or whether it lies in a window of the “open world”. This guarantees that the avionics world can take over command of the pointer if it exits the window of the open world, the pointer not having to remain disabled in a window of the open world if the latter behaves in an erroneous manner.
The management of the displacement of the pointer in the “avionics world” is not immediate and depends inter alia:                on the functions presented on the screen:                    there exist windows where interactivity is prohibited. For example, the screens of “PFD” (Primary Flight Display) type must not comprise any pointers            there exist windows belonging to the “open world”                        on the configuration of the screens:                    on a screen wall, it is necessary to be capable of passing from one screen to another by continuity.                        
This complex management can only be ensured by a function that masters the cockpit context. It may not be ensured by the CCD whose electronics and computing are necessarily rudimentary. This complex management is ensured by the avionics system and in particular by the viewing devices. Consequently, in the “avionics world”, the CCD works simply in relative coordinates. When the user uses the CCD to move the corresponding pointer on a viewing screen of the “avionics world”, the information sent by the CCD is the relative displacements dX and dY performed by the user from an initial position. Electronic means disposed in the viewing screen then calculate, on the basis of the knowledge of its relative displacements dX and dY, the absolute displacements X and Y on the screen proper. Thus, the viewing device can control whether the displacement is authorized, if it entails a change of screen, etc. These things would all be impossible if the CCD worked in absolute coordinates.
Of course, in the “open world”, the pointer's display constraints are reduced and, for reasons of speed of display, it is more beneficial for the CCD to work in absolute coordinates X and Y.
When it is necessary to manage a CCD making it possible to move a cursor at one and the same time in the “avionics world” and the “open world”, it is therefore necessary to generate relative coordinates destined for the “avionics world” and absolute coordinates destined for the “open world”, while preserving the security of the “avionics world”.
A first possible solution is presented in FIG. 2. This figure represents the “avionics world” 1, the “open world” 2 and their interconnection. The “avionics world” and the “open world” are represented by dotted rectangles with rounded edges. In this figure, five viewing devices 1 are represented. The two left viewing devices provide information to a first user, generally the captain, and the two right viewing devices provide information to a second user, generally the flight officer. The central viewing device is common to both users. Of course, this number of viewing devices is given only by way of indication. It could be lower or higher. These five devices are interconnected with an avionics bus 3 which ensures the linkup between the viewing devices and the remainder of the avionics world. These viewing devices receive instructions from the two users by means of the two CCDs 4 through a so-called “interactivity” bus 5. The linkup between the “avionics world” and the “open world” is ensured by an “avionics world”-“open world” gateway 6 which, through the “avionics world”, controls the “open world” via a one-way gateway. In this configuration, the operation of the CCDs toward the “open world” is as follows:                sending of the relative coordinates of a CCD to the avionics world,        calculation of the absolute coordinates of the CCD by the avionics world,        retransmission of the coordinates of the CCD to the open world, via the avionics world/open world gateway,        recovery of the coordinates of the CCD by the open world,        generation of the pointer in the video destined for the screens.        
This implementation exhibits a major drawback: the latency of the pointer for the open world is much more significant than the latency of the pointer for the avionics world, and more significant than the maximum latency of 100 milliseconds authorized by the “A661” reference aeronautical standard. In order to decrease the latency of the pointer in the open world, the CCD must work in multi-mode according to the position of the pointer.